Chain and sprocket transmission



Dec. 9, 1952 J. E. RADDINGS CHAIN AND SPROCKET TRANSMISSION Filed Dec. 18. 1948 10a FlG. l7 Fl Patented Dec. 9, 1952 UNITED STATES PTENT OFFICE 'JHy-F:

CHAIN AND SI ROCKET TRANSMISSION James Ernest Raddings, Totland Bay,

. Isle of Wight Application. December 18, 1948, Serial No. 66,074

In Great Britain December 19, 1947 H end, or if turned over, the chain cannot engage the sprocket teeth. Such transmissions have particular, although not exclusive, application in aircraft control systems whereby remote parts such as flaps or rudder surfaces, or fuel or oil control valves, are required to be moved from the cockpit. Such control systems nor mally comprise a combination of elements working in tension, such as cables, rods, and chains, the chains passing over driving or driven sprockets to transmit the controlling effort to the part tobe' moved. Since the controlled part is generally required to be moved positively in either direction, and the control elements operate only in tension, each control system normally comprises parallel channels, and unless careful precautions are taken it is frequently possible to cross thetwo channels of a control system so that the controlled part is moved oppositely to the desired direction.

In spite of such precautions as the use of different sizes or types of connectors for elements in one channel to those in the other, control systems have still become crossed due to the possibility of reversing a chain end for end and crossing over its end connectors, or of wrapping a chain round a sprocket in the wrong direction, and it is an object of the present invention to provide a construction whereby this is impossible.

In a chain and sprockettransmission according to the present invention, both the chain and the sprocket are provided asymmetrically with interengageable formations which prevent engagement between the pins or rollers of the chain and the teeth of the sprocket in any but a predetermined attitude of the chain relative to the sprocket.

Preferably the interengaging formations comprise a bridge piece connecting the two sides of a link along the one edge thereof so as to engage the sprocket teeth only when this edge of the chain is presented to the sprocket and thus to prevent engagement of the pins or rollers of the chain with the sprocket teeth, in combination with a lateral projection on one only of the said link sides to co-operate with a projection on one side only of'the sprocket for preventing engagement of the pins or rollers of the chain with the sprocket teeth when the chain is pre- 15 Claims. (01. 74-243) sented thereto with the projections on both'the link and the sprocket on the same side of the sprocket teeth. A

In order that the invention may be more clearly understood, alternative constructions of chain and sprocket in accordance therewith will now be described by way of example with reference to the accompanying drawings in which:

Fig. 1 is a general diagrammatic view of a; chain and sprocket portion of a conventional form of flexible transmission showing the different a'rrangements of the end connections'to adjacent cable sections; i

Fig. 2 is a top perspective view of two links'of a non-reversible chain constructed in accordance with the present invention; 1 I I Fig. 3 is an under perspective view of severa links of the chain illustrated in Fig. 2; 1 I

Fig. 4 is an enlarged end view of the asymmetrical link shown in Figs. 2 and 3; Fig. 5 is an underplan view of the link of Fig. 4;

Fig. 6 is a side elevation on the line VI of Fig. 5; Fig. 7 is a fragmentary sectional view of one form of asymmetrical sprocket and chain link according to the present invention;'

Fig. 8 is an end elevation of an alternative form of asymmetrical link; I 1

Fig. 9 is an end elevation of a further alternative form of asymmetrical link; 6

Fig. 10 is a fragmentary side elevation of another form of sprocket showing a chain incorporating the links of Fig. 9 incorrectly presented thereto;

Fig. 11 is a sectional elevation on the line Xl-Xl of Fig. 10;

Fig. 12 is a sectional elevation of another form of asymmetrical link;

Fig. 13 is a side elevation of the link shown in Fig.12; Fig. 14 is a sectional elevation of a sprocket for use with the asymmetrical link of Fig. 12,

Fig. 15 shows in section an alternative construction of asymmetrical link, and.

Fig. 16 shows a still further alternative-con struction of asymmetrical link. i

Fig. 1 illustrates diagrammatically a portion, including a chain and sprocket stage, of a flexible transmission system of conventional construction such as is commonly used in, say, aircraft for controlling flaps, rudders, or'the like. The chain I passes round the sprocket 2 which is keyed on a shaft 3 whose angular position is to be controlled from a remote point The chain is to be connected at its ends to two cables 4, by means of respective connectors 6, I, the connector 6 engaging a small pin 8 at one end of the chain I while the connector I engages a large pin 9 at the other end of the chain. The difference in size of the pins 8, 9, with the consequent difierences in the two connectors 6, I, is normally :relied upon to prevent incorrect connectionof the chain I to the cables 4, 5, but it will be apparent that, with a chain which is symmetrical about the plane containing the axes of its pins or rollers, the crossing of the chain I and its passage round the sprocket 2 in the reverse direction, as indicated by .thefldotted lines Ia, cannot be positively prevented by the use of dissimilar end connectors 6, I. Theriskof this incorrect connection is increased where, inactual practice, the diameter of the sprocket 2 is small compared with the length ofjthe chain section I, and the latter is passed round several zggnidey pulleys cr-sprockets in; different planes before-connectionyto the cables- 4, .5.

'Fig. 2 illustrates a pair of adjacentlinks 45,! I -9 ;a. non-reversiblechain I and Fig. 3 illustrates ":3: section of "this chain. The link-II is Ianormal .inner dink-of -a standard roller chain, but the -.-link I I) :is of asymmetrical construction (see also Figs. 4-6) having a bridgepiece I2.connecting wthe'iouter-edges ofthe link sides, and discs I3 .-:mountedonv the aends of ther pivot pins I4 of the -chain-roilers-I-5. The bridge piece I2 is preferaably; iormedintegral with the link sides and is of relatively narrow width in the direction .of the chain I. The discs I3 maybe constituted whither rby washers -or-.-integral headson the connecting pins I4, and-having a diameter substantiallyequal to the-diameter-of a roller I5-of the chain I.

:Referring now to Fig-"I, the sprocket i6 is provided onv one, face-thereof with an annular tiplatei I] :which is: secured, as by rivets '18, to the sprocket and has an outer diameter. equal 'itojthe-zsprocket diameter measured across the tips of the teeth I9. The other side of the sprocket -I-6xis left-,free, and the lateral clear- =.ance'20*between the adjacent flanks Ha of the sprocket teeth I9 and-the inner surface of the 'v annular-plate "I I issuch as to afford free entry of the plain sides Illw'of theouterlin-ks 1-0 of the chain 1.

If, however, the'chain I is presented to the sprocket ,I.6"so that the washersor heads I3 are .on the :same side of the; sprocket teeth I t asithe annularrplate. III, the rimof the 'latterengages the said washers or heads I3 and prevents the rrollers; I5ztircmgengaging :the sprocket x'teeth is. The chain I must thereforebe reversed-endfcr riend' before. ,it; can be-engaged with the sprocket. Similarly, if the chain I is turnedtover so that ".thepbridgie pieces I2 are on the. inside of'the chain I, towards the axis of the sprocket H5, '-1:hese bridge pieces iI-2 will engageithe tips of thetee'thllil andra'gain'prevent the rollers I5 irom bieing engaged thereby. The-chain I must therefore be turned over-e. g. by 'uncrossing- -:or:=bewrapped around the sprocket IS on the" IS in which the two parts can mesh together.

correctly, and hence the risk of crossing the con- .trol connections by "incorrectly assembling the '$chain--and sprocket transmission .is eliminated.

.Therezare fourgpossibleattitudes of the chain vthechain end .for end so that its right hand end'is 'in'the left hand position and vice versa.

.fIhe chain stilli'makes contact with the sprocket,

however, on the correct side of the sprocket axis. In the third alternative position, the chain has itsright'sand left "hand ends in their correct position but is engaged with the sprocket on the wrong side of its axis. This is equivalent to taking the chain in its first or correct attitude and turning .it about .its longitudinal v-axis through .1803.

In the fourth possiblesattitude, the chain ..is .reversed-,.end forend and engages the; sprocket on the wrong .side of its axis.

Instead of providing thepins IA with enlarged heads .or washers I3, theirceed'ge of theside Iflbof a bridgedlink It! may be provided with .a small out-.turnednprojection 10c (Fi .-8) of a length .suiiicientto engage the-rim of the annular plate IIs'hould the chain "I be. incor- .rectly presented to .the sprocket 'ISso that this side Hill) of the bridged .link faces'in jthesame direction .as the sideof the sprocket I6 to which theplate I] is .secured.

Fig. .9..sh0ws a still furtherli'orm 'ofLlink I0 in which the .one ends of. 'thepins Mare provided ,with projecting .domedheads 2| of a size to prevent their entry into the clearance space v200i Various alternative arrangements of ,sproc'ket Idmaybe adopted as desired. "Florrexample, the annularplate I! may beformed integralwith the sprocket 1.6 or itmaylbe weldedthereto. .Its external diameter may also :be varied.1in-.c0r1espondence with variations in the sizeofthe-enlargedhead M or washer I3 on thepins-M, or the depth, considered radiallyof the .sprocket .I 6,.of

sprocket IBadjacentthe teeth I9 toenga e the lateral projections Illc (Fig. 8) on the links I0.

Instead of? providing one side Iflb 'of1a bridged slink 1.9 with a small out-turned projection- I00 of a length sufficient to engage the projections -22 or the rim of the annular plate "CL should the chain I be incorrectly presented to the sprocket 16, the 'said side Iflbof the bridged link III may the provided with a flat depending projection lild (Figs. 12 and 13) to lie in ,a-wplane parallel to the plane of thesprocket I6, and the latter may be provided with a shoulder Ita -of a diameter to engage the extremity of.-.the*said projection lfld, in such away-as to preventengagementcf the pins or rollers 15 of: the-chain I with the sprocket teeth I9 when the chainis presented to the sprocket in the incorrect way,:as indicated at the top--of-Figl'14.

'Fig. 15 illustratesin section an alternative method of construction 10f 1 an asymmetrical link The link .consists :ofa standard -formtof :kelat'we-to .;the-.- sprocket. If :the .chain.. ';is sirelinkside.110a=-and1aspecia1iorni of side. H2012.

"ga es-26 The latter has an integral tongue l lzformed centrally of its length along one edge and bent over laterally inwards to form a bridge piece extending as far as the side IIIIa. The other edge of the side IIIlb may be bent outwards to form a lateral projection II 00 or extended in its own plane to form a projection IIIld, shown dotted. Alternatively again, the projection N00 or IIIld may be omitted and the standard connecting pin I4 lengthened to accommodate a washer I3 or formed to a head as shown at 2| in Fig. 9.

Fig. 16 shows an alternative construction of the link shown in Fig. 4-6, in which the washers I3 are replaced by a standard link side IIIIa, the part circular end formations I 311 simulating the washers I3 in appearance and function. In all forms of asymmetrical link III, the bridge piece may be separately attached, as by welding, to one or both link sides Illa, I 0b after assembly thereof on the pins I4.

Figs. 1'7, 18 and 19 illustrate a, still further form of construction of chain and sprocket transmission according to the invention. The chain I consists partly or wholly of links I0 having their sides Illa, Iflb of the same size and shape with integral lateral projections IIIc on the one edge thereof. In the form shown in Fig. 17, the link sides Illa, IIlb are assembled with the projections Iflc outwardly directed and located on opposite edges, the projection I00 on the link side Illa 1 being operative to engage the rim of the disc H to prevent engagement of the chain I with the sprocket I6 should the chain be reversed end for end. Furthermore, if the chain is to be passed, in opposite directions around two closely adjacent sprockets I6, the arrangement of the projections I00 prevent engagement of the chain with both sprockets I6 in any but the correct manner.

In the form shown in Fig. 18, the link side I0!) is reversed with respect to the arrangement shown in Fig. 1'7 so that its projection We is turned inwards and is operative to engage the sprocket teeth I9 if the chain is presented to the sprocket It for wrapping in the wrong direction. Similarly, if the chain is reversed end for end, the projection I00 on the other link side Illa engages the rim of the disc IT. The chain I can thus only be engaged with sprocket I6 in one relative attitude.

The sprocket I6 is preferably arranged in all cases so that it can only be assembled on its shaft one way round. For example, it may be provided with a concentric recess Ilia on one side to engage a corresponding shoulder on the shaft (not shown). It will be understood that where the chain I has only a limited travel with respect to the sprocket I6, the asymmetrical links III need only be provided over that length thereof which engages the sprocket teeth I9.

What I claim is:

1. A chain and sprocket transmission comprising a chain incorporating a link having an asymmetrical formation, and a sprocket having an asymmetrical formation to coact with the said formation on the chain link for preventing driving inter-engagement of the chain with the sprocket in all relative positions of the chain and sprocket save one.

2. A chain and sprocket transmission comprising a sprocket having an asymmetrical lateral projection, a chain incorporating a link having a formation on an edge thereof to engage the tips of the sprocket teeth when the chain is presented to the sprocket in the inverted position and a projection on one side thereof engageable with the asymmetrical lateral projection on the sprocket when the chain is presented to the sprocket in the wrong sense.

3. A chain and sprocket transmission comprising a sprocket having an asymmetrical formation and a chain consistin of alternate symmetrical and asymmetrical links, the asymmetrical formation on the latter being engageable with the asymmetrical formation on the sprocket to prevent driving interengagement of the chain therewith in all relative positions of the chain and sprocket save one. I

4. A chain and sprocket transmission having an asymmetrical sprocket and chain link having an inwardly directed formation on one edge thereof to engage the tip of a sprocket tooth when the link is presented to the sprocket upside down, and a projection on one side thereof to engage the asymmetrical formation on the sprocket when the link is presented thereto the wrong way round.

5. In a chain and sprocket transmission as claimed in claim 4, a chain link having a bridge piece connecting the corresponding one edges of the link sides.

6. In a chain and sprocket transmission as claimed in claim 5, a chain link having a lateral projection on the edge opposite to the bridge piece and .a sprocket having a co'acting formation adjacent the one flank of a sprocket tooth.

7. In a chain and sprocket transmission as claimed in claim 4, a chain link having a projection lying in the plane of one side of the link and a sprocket having an annular shoulder on one side face thereof to engage the said projection when the link is presented to the sprocket the wrong way round and so prevent driving engagement of the link with a sprocket tooth.

3. In a chain and sprocket transmission as claimed in claim 4, a chain link having 'a radially enlarged formation on the one end of each link connecting pin and a sprocket having a formation on the one face thereof to coact with the said radially enlarged formation for preventing driving engagement of the link With a sprocket tooth when the link is presented to the sprocket the wrong way round.

9. In a chain and sprocket transmission as claimed in claim 1, a chain link wherein the asymmetrical formation thereon comprises a bridge piece connecting the edges of the link sides and a projection on the opposite edge of one of the sides, and a sprocket having a formation on one side face thereof to coact with the said projection on the link side for preventing incorrect engagement of the link with the sprocket.

10. In a chain and sprocket transmission as claimed in claim 1, a chain link having two separate sides wherein the asymmetrical formation on the link comprises a laterally inward projection on one edge of one side extending towards the corresponding edge of the other side.

11. In a chain and sprocket transmission as claimed in claim 1, a chain wherein the asymmetrical formation thereon includes a lateral projection on one side of a link and a sprocket having an asymmetrical formation constituted by an annular plate located adjacent the one flanks of the sprocket teeth and spaced therefrom by a clearance space for accommodating the sides of the chain links not provided with an asymmetrical formation when the chain -is correctly presented to the sprocket.

12. In a chain and sprocket transmission as claimed in =claim,1, a chain wherein the asym- 1 provided with an asymmetrical formation when the chain is correctly presented to the sprocket.

13. In a chain and sprocket transmission as claimed in claim 1, a chain wherein the asymmetrical formation thereon com-prises a projection on one edge of a side of a chain link and a sprocket having an annular shoulder on one side thereof adjacent the roots of the teeth for coac ing with the said projection on a chain link to prevent incorrect engagement of the link with the said sprocket tooth.

14. In a chain and sprocket transmission as claimed in claim 1, a chain link having two separate sides wherein the asymmetrical formation on the link comprises a laterally inward projection on one edge of one side extending towards the corresponding-edge of'the other side and a projection formed on the opposite edge thereof.

15. A chain and sprocket transmission system comprising a chain and sprocket wherein there is one correct attitude of the chain relative to '8 the sprocket; coacting formations on the..chain and sprocket, respectively, for preventingjd'riving interengagement of the chain and the sprocket when saidchain is reversed end for end fromthe correct attitude thereof and said chain engages said sprocket on the correct side of the sprocket axis, and a further formation on the chain for preventing driving interengagement of the chain and sprocket whenthe ends of said chain are in their correct attitudes but the chain engages said sprocket on the opposite side of the sprocket axis from that engaged when the chain is in its correct attitude or when said chain is reversed end for end and engages said sprocket on the opposite side of the sprocket axis from that engaged when the chain is in its correctatt'itude.

JAMES ERNEST RADDINGS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 618,683 Gentry Jan. 24, 1899 1,508,446 Diehl Sept. 16, 1924 1,813,011 Adams July '7, 1931 

